Abstract: In order to accurately describe the dynamic performance of the semi-rigid frame connected by mortise-tenon joints under seismic excitation, a nonlinear rotational spring is used to simulate the rocking behavior of the column under earthquake. Based on the nonlinear restoring force models of the column, the mortise-tenon joints and the bracket sets, a lumped mass model is proposed for seismic analysis of a single-storey palace-style timber structure, and the nonlinear time history analysis under seismic excitation is carried out. By comparing the time history curve of the calculated model and shaking table test results, it is found that the error between the calculated value and the experimental value without considering column rocking is relatively large. The error between the calculated peak value of the time history curve considering rocking effect and the experimental peak value is relatively small, and the peak values occur nearly at the same time. Based on the simplified model, a further parametric analysis is carried out, which shows that the vertical load can significantly reduce the seismic displacement response of the palace-style timber structure. The higher the column height, the greater the seismic displacement response of the structure. The seismic displacement response of the structure decreases significantly with the increase of the rotational stiffness of the mortise-tenon joints, and the increase of the number of bracket sets increases the lateral stiffness of the column frame, thereby reducing the seismic displacement response of the structure. The research results can provide a calculation basis for the performance evaluation of ancient timber structures under earthquake.